Developments and Controversies in Invasive Diagnosis of Coronary Microvascular Dysfunction in Angina With Nonobstructive Coronary Arteries.

Approximately half of all coronary angiograms performed for angina do not show obstructive coronary artery disease, and many of these patients have coronary microvascular dysfunction (CMD). Invasive testing for CMD has increased with the advent and wider availability of thermodilution systems. We review CMD pathophysiology and invasive diagnostic testing using the Doppler and thermodilution systems. We report the results of a PubMed search of invasive microvascular testing and discuss limitations of current diagnostic algorithms in the diagnosis of CMD, including controversies regarding the optimal cutoff value for abnormal coronary flow reserve, use of microvascular resistance indices, and options for increasing sensitivity of testing.

Sex differences in plaque characteristics of fractional flow reserve-negative non-culprit lesions after myocardial infarction.

BACKGROUND AND AIMS: Recurrent events after myocardial infarction (MI) are common and often originate from native non-culprit (NC) lesions that are non-flow limiting. These lesions consequently pose as targets to improve long-term outcome. It is, however, largely unknown whether these lesions differ between sexes. The aim of this study was to assess such potential differences. METHODS: From the PECTUS-obs study, we assessed sex-related differences in plaque characteristics of fractional flow reserve (FFR)-negative intermediate NC lesions in 420 MI-patients. RESULTS: Among the included patients, 80 (19.1 %) were female and 340 (80.9 %) male. Women were older and more frequently had hypertension and diabetes. In total, 494 NC lesions were analyzed. After adjustment for clinical characteristics and accounting for within-patients clustering, lesion length was longer in female patients (20.8 ± 10.0 vs 18.3 ± 8.5 mm, p = 0.048) and minimum lumen area (2.30 ± 1.42 vs 2.78 ± 1.54 mm2, p < 0.001) and minimum lumen diameter (1.39 ± 0.45 vs 1.54 ± 0.44 mm, p < 0.001) were smaller. The minimum fibrous cap thickness was smaller among females (96 ± 53 vs 112 ± 72 µm, p = 0.025), with more lesions harboring a thin cap fibroatheroma (39.3 % vs 24.9 %, p < 0.001). Major adverse cardiovascular events at two years occurred in 6.3 % of female patients and 11.8 % of male patients (p = 0.15). CONCLUSIONS: FFR-negative NC lesions after MI harbored more high-risk plaque features in female patients. Although this did not translate into an excess of recurrent events in female patients in this modestly sized cohort, it remains to be investigated whether this difference affects clinical outcome.

Chronic acetylcholinesterase inhibition reduces the effects of physical training on ventricular contractility and coronary bed reactivity in hypertensive rats.

Systemic arterial hypertension is accompanied by autonomic impairments that, if not contained, promotes cardiac functional and morphological damages. Pyridostigmine bromide (PYR) treatment results in positive effects on autonomic control and beneficial cardiac remodeling. These findings were also observed after aerobic physical training (APT). However, little is known about PYR effects on left ventricular contractility, mainly when it is combined with APT. We aimed to investigate the effects of chronic acetylcholinesterase inhibition on cardiac autonomic tone balance, coronary bed reactivity, and left ventricular contractility in spontaneously hypertensive rats (SHR) submitted to APT. Male SHR (18 weeks) were divided into two groups (N = 16): untrained and submitted to APT for 14 weeks (18th to 32nd week). Half of each group was treated with PYR (15 mg/kg/day) for two weeks (31st to 32nd week). The experimental protocol consisted of recording hemodynamic parameters, double autonomic blockade with atropine and propranolol, and assessment of coronary bed reactivity and ventricular contractility in isolated hearts using the Langendorff technique. PYR and APT reduced blood pressure, heart rate, and sympathetic influence on the heart. The Langendorff technique showed that APT increased coronary perfusion pressure and left ventricle contractility in response to coronary flow and ß-agonist administration. However, treatment with PYR annulled the effects of APT. In conclusion, although chronic treatment with PYR reduces cardiac sympathetic tonic influence, it does not favor coronary bed reactivity and cardiac contractility gains. PYR treatment in the trained SHR group nullified the coronary vascular reactivity and cardiac contractility gains.

Myocardial infarction with non-obstructive coronary arteries in a young seropositive woman with human immunodeficiency virus: a case report and review of the literature.

BACKGROUND: Elevated susceptibility to acute myocardial infarction and various cardiovascular diseases has been observed in individuals infected with the human immunodeficiency virus compared with the uninfected population, as demonstrated in numerous studies. The precise mechanism by which human immunodeficiency virus infection heightens the risk of acute myocardial infarction remains elusive. The manifestation of acute coronary syndrome in young patients with human immunodeficiency virus may deviate from the typical, displaying distinct pathophysiological and clinical characteristics. The occurrence of myocardial infarction with non-obstructive coronary arteries in young patients with human immunodeficiency virus poses diagnostic and treatment challenges. CASE PRESENTATION: We present the case of a 46-year-old African woman with no traditional atherosclerotic risk factors. She was diagnosed with human immunodeficiency virus-1 infection 2 years prior to her current admission for chest pain. Her troponin levels were elevated, suggestive of acute coronary syndrome. Although coronary angiography ruled out coronary artery stenosis, it revealed mild myocardial bridging in the left anterior descending artery. Cardiac magnetic resonance imaging confirmed myocardial infarction, indicating a myocardial infarction with non-obstructive coronary arteries with an apical thrombus in the left ventricle. Following medical treatment, the patient experienced resolution of chest pain and improvement in ST-segment elevation. CONCLUSIONS: In young female patients without traditional risk factors, human immunodeficiency virus infection is a possible etiological factor for myocardial infarction with non-obstructive coronary arteries. The likely pathophysiological pathway is superficial endothelial cell denudation as a result of chronic inflammation and immune activation.

Myocardial contrast echocardiography evaluation of coronary microvascular dysfunction to Predict MACEs in patients with heart failure with preserved ejection fraction follow-up.

BACKGROUND: CMD refers to the abnormalities of the tiny arteries and capillaries within the coronary artery system, which result in restricted or abnormal blood flow. CMD is an important mechanism involved in ischemic heart disease and secondary heart failure. CMD can explain left ventricular dysfunction and poor prognosis.The European Association of Cardiovascular Imaging recommends the use of MCE for the assessment of myocardial perfusion. Myocardial contrast echocardiography (MCE) is used to evaluate the accuracy of Coronary microvascular dysfunction (CMD) for predicting major adverse cardiac events (MACEs) in patients with heart failure with preserved ejection fraction (HFpEF) at follow-up. METHODS: The clinical data of 142 patients diagnosed with HFpEF in our hospital from January 2020 to January 2022 were retrospectively summarized and stratified into 77 cases (> 1) in the CMD group and 65 cases (= 1) in the non-CMD group based on the perfusion score index (PSI) of the 17 segments of the left ventricle examined by the admission MCE, and the perfusion parameters were measured at the same time, including the peak plateau intensity (A value), the curve slope of the curve rise (ßvalue) and A × ß values. At a median follow-up of 27 months till October 2023, MACEs were recorded mainly including heart failure exacerbation, revascularization, cardiac death, etc. RESULTS: Increasing age, hypertension, diabetes, and coronary artery disease in the CMD group resulted in decreased left ventricular ejection fraction (LVEF), increased plasma NT-B-type natriuretic peptide (BNP) and left ventricular global longitudinal strain (LVGLS), decreased A-values and A × ß-values, and an increased incidence of MACEs (P < 0.05). Univariate and multivariate Cox regression analyses showed that LVGLS (HR = 1.714, 95% CI = 1.289-2.279, P < 0.001) and A × ß values (HR = 0.636, 95% CI = 0.417 to 0.969, P = 0.035) were independent predictors of MACEs in patients with HFpEF. The receiver operating characteristic curve (ROC) showed that the area under the curve (AUC) of LVGLS combined with A × ß value for diagnosis of MACEs was 0.861 (95% CI = 0.761 ~ 0.961, P < 0.001), which was significantly higher than that of LVGLS or A × ß value (P < 0.05). The Kaplan-Meier survival curves showed that the cumulative survival rate in CMD group was significantly lower than non-CMD group (logrank χ2 = 6.626, P = 0.010), with the most significant difference at 20 months of follow-up. CONCLUSION: MCE can evaluate CMD semi-quantitatively and quantitatively, LVGLS combined with A × ß value has good performance in predicting the risk of developing MACEs in patients with HFpEF at 3 years of follow-up, and CMD can be used as an important non-invasive indicator for assessing clinical prognosis.

Value of Ischemia and Coronary Anatomy in Prognosis and Guiding Revascularization Among Patients With Stable Ischemic Heart Disease.

BACKGROUND: The value of physiological ischemia versus anatomic severity of disease for prognosis and management of patients with stable coronary artery disease (CAD) is widely debated. METHODS: A total of 1764 patients who had rest-stress cadmium-zinc-telluride single-photon emission computed tomography myocardial perfusion imaging and angiography (invasive or computed tomography) were prospectively enrolled and followed for cardiac death/nonfatal myocardial infarction. The CAD prognostic index (CADPI) was used to quantify the extent and severity of angiographic disease. Prognostic value was assessed using Cox models, adjusted for pretest risk, known CAD, stressor, left ventricular ejection fraction, %ischemia and infarct, CADPI, and early (90-day) revascularization. Incremental prognostic value was evaluated using net reclassification index. RESULTS: The mean age was 69.7±9.5 years, 24.4% were women, and 29.3% had known CAD. Significant ischemia (>10%) was present in 28.4%. Nonobstructive, single, and multivessel disease was present in 256 (14.5%), 772 (43.8%), and 736 (41.7%), respectively. Early revascularization occurred in 579 (32.8%). Cardiac death/myocardial infarction occurred in 148 (8.4%) over a 4.6-year median follow-up. Both %ischemia and CADPI provided independent and incremental prognostic value over pretest clinical risk (P<0.001). In a model containing both ischemia and anatomy, ischemia was prognostic (hazard ratio per 5% ↑, 1.35 [95% CI, 1.11-1.63]; P=0.002) but CADPI was not (hazard ratio per 10-unit ↑, 1.09 [95% CI, 0.99-1.20]; P=0.07). Early revascularization modified the risk associated with %ischemia (interaction P=0.003) but not with CADPI (interaction P=0.6). %Ischemia and single-photon emission computed tomography variables added incremental prognostic value over clinical risk and CADPI (net reclassification index, 20.3% [95% CI, 9%-32%]; P<0.05); however, CADPI was not incrementally prognostic beyond pretest risk, %ischemia, and single-photon emission computed tomography variables (net reclassification index, 3.1% [95% CI, -5% to 15%]; P=0.21). CONCLUSIONS: Ischemic burden provides independent and incremental prognostic value beyond CAD anatomy and identifies patients who benefit from early revascularization. The anatomic extent of disease has independent prognostic value over clinical risk factors but offers limited incremental benefit for prognosis and guiding revascularization beyond physiological severity (ischemia).

Computing pulsatile blood flow of coronary artery under incomplete boundary conditions.

BACKGROUND: Accurate measurement of pulsatile blood flow in the coronary arteries enables coronary wave intensity analysis, which can serve as an indicator for assessing coronary artery physiology and myocardial viability. Computational fluid dynamics (CFD) methods integrating coronary angiography images and fractional flow reserve (FFR) offer a novel approach for computing mean coronary blood flow. However, previous methods neglect the inertial effect of blood flow, which may have great impact on pulsatile blood flow calculation. To improve the accuracy of pulsatile blood flow calculation, a novel CFD based method considering the inertia term is proposed. METHODS: A flow resistance model based on Pressure-Flow vs.Time curves is proposed to model the resistance of the epicardial artery. The parameters of the flow resistance model can be fitted from the simulated pulsating flow rates and pressure drops of a specific mode. Then, pulsating blood flow can be calculated by combining the incomplete pressure boundary conditions under pulsating conditions which are easily obtained in clinic. Through simulation experiments, the effectiveness of the proposed method is validated in idealized and reconstructed 3D model of coronary artery. The impacts of key parameters for generating the simulated pulsating flow rates and pressure drops on the accuracy of pulsatile blood flow calculation are also investigated. RESULTS: For the idealized model, the previously proposed Pressure-Flow model has a significant leading effect on the computed blood flow waveform in the moderate model, and this leading effect disappears with the increase of the degree of stenosis. The improved model proposed in this paper has no leading effect, the root mean square error (RMSE) of the proposed model is low (the left coronary mode:≤0.0160, the right coronary mode:≤0.0065) for all simulated models, and the RMSE decreases with an increase of stenosis. The RMSE is consistently small (≤0.0217) as the key parameters of the proposed method vary in a large range. It is verified in the reconstructed model that the proposed model significantly reduces the RMSE of patients with moderate stenosis (the Pressure-Flow model:≤0.0683, the Pressure-Flow vs.Time model:≤0.0297), and the obtained blood flow waveform has a higher coincidence with the simulated reference waveform. CONCLUSIONS: This paper confirms that ignoring the effect of inertia term can significantly affect the accuracy of calculating pulsatile blood flow in moderate stenosis lesions, and the new method proposed in this paper can significantly improves the accuracy of calculating pulsatile blood flow in moderate stenosis lesions. The proposed method provides a convenient clinical method for obtaining pressure-synchronized blood flow, which is expected to facilitate the application of waveform analysis in the diagnosis of coronary artery disease.

Changes in absolute coronary flow and microvascular resistance during exercise in patients with ANOCA.

BACKGROUND: Whether saline-induced hyperaemia captures exercise-induced coronary flow regulation remains unknown. AIMS: Through this study, we aimed to describe absolute coronary flow (Q) and microvascular resistance (Rµ) adaptation during exercise in participants with angina with non-obstructive coronary artery disease (ANOCA) and to explore the correlations between saline- and exercise-derived coronary flow reserve (CFR) and microvascular resistance reserve (MRR). METHODS: Rµ, Q, CFR and MRR were assessed in the left anterior descending artery using continuous thermodilution with saline infusion at 10 mL/min (rest), 20 mL/min (hyperaemia) and finally at a 10 mL/min infusion rate during stress testing with a dedicated supine cycling ergometer. An incremental workload of 30 watts every two minutes was applied. A saline-derived CFR (CFRsaline) cutoff <2.5 was used to identify coronary microvascular dysfunction (CMD). RESULTS: CFRsaline-defined CMD was observed in 53.3% of the participants (16/30). While cycling, these patients less of an ability to increase Q (7 [interquartile range [IQR] 30.5-103.0] vs 21 [IQR 5.8-45.0] mL/min/30 watts; p=0.01) due to a smaller decrease of Rµ (109 {IQR 32-286} vs 202 [IQR 102-379] Wood units [WU]/30 watts; p<0.01) as compared with the group with normal CFRsaline. In the overall population, CFRsaline and exercise-derived CFR (CFRexercise) were 2.70±0.90 and 2.85±1.54, respectively, with an agreement classification of 83.3%. A good correlation between saline and exercise techniques for both CFR (r=0.73; p<0.0001) and MRR (r=0.76; p<0.0001) was observed. Among participants with normal CFRsaline, 28.7% (4/14) had an impaired CFRexercise <2.5 at the peak of exercise due to a moderate and late decrease of Rµ. CONCLUSIONS: Saline-induced hyperaemia provided a valid surrogate for exercise physiology independently of the absolute level of CFR and MRR, although exercise provided more granularity to evaluate adaptation among participants with exercise-related CMD.

Diagnostic Performance of Fractional Flow Reserve Derived From Coronary CT Angiography: The ACCURATE-CT Study.

BACKGROUND: AccuFFRct (ArteryFlow Technology) is a novel noninvasive method for calculating fractional flow reserve (FFR) from coronary computed tomography angiography (CCTA). The accuracy of AccuFFRct has not been adequately assessed. OBJECTIVES: This study sought to evaluate the diagnostic performance of AccuFFRct in detecting lesion-specific ischemia. METHODS: This prospective study enrolled 339 patients with 404 vessels. CCTA-derived FFR was calculated using an on-site computational fluid dynamics-based method and compared with invasive FFR. The performance of AccuFFRct was comprehensively analyzed in all lesions and subgroups, including "gray zone" lesions, various lesion classifications, clinical presentations, stenosis severities, and lesion locations. RESULTS: Using FFR ≤0.80 as a reference standard, the overall diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for AccuFFRct were 90.6% (95% CI: 87.3%-93.3%), 90.9% (95% CI: 85.1%-94.9%), 90.4% (95% CI: 86.1%-93.8%), 85.3% (95% CI: 79.8%-89.5%), and 94.2% (95% CI: 90.8%-96.4%), respectively. Good correlation and agreement were found between the computed AccuFFRct and measured FFR. AccuFFRct showed superior discrimination ability to CCTA (AUC: 0.93 [95% CI: 0.89-0.95] vs 0.77 [95% CI: 0.72-0.81]; P < 0.001) and quantitative coronary angiography (AUC: 0.93 [95% CI: 0.89-0.95] vs 0.89 [95% CI: 0.85-0.92]; P = 0.048) for identifying functionally significant stenosis. Notably, AccuFFRct maintained high diagnostic accuracy across the spectrum of lesion classifications, clinical presentations, stenosis severities, lesion locations, and in the "gray zone". Furthermore, in the cohort with ≥70% stenosis, AccuFFRct could significantly reduce the rate of un-necessary invasive tests (33.1% vs 6.6%; P < 0.001). CONCLUSIONS: The study confirms the potential of AccuFFRct as a noninvasive alternative to invasive FFR for detecting ischemia in coronary artery disease and to risk stratify patients. The results highlight AccuFFRct's robust diagnostic ability across a wide range of lesion classifications, clinical presentations, stenosis severities, lesion locations, and in the "gray zone". (Diagnostic Performance of Fractional Flow Reserve Derived From Coronary CT Angiography [ACCURATE-CT]; NCT04426396).

A new animal model of cardiorenal syndrome could be established by inducing heart failure through coronary artery ligation in spontaneously hypertensive rats.

In rats with unilateral nephrectomy and cardiac dysfunction, renal function deteriorates at an accelerated rate, as evidenced by increased proteinuria. Whether myocardial infarct-induced heart failure (HF) exacerbates renal injury in hypertensive rats with mild renal injury has not been reported. Rats underwent either coronary ligation or sham surgery. Thirty spontaneously hypertensive rats (SHRs) aged 8 weeks were randomly divided into two groups. Group 1 was the sham group, in which the rats underwent thoracotomy without ligation of the coronary artery. Group 2 underwent coronary artery ligation. The rats in group 2 underwent coronary artery ligation on week 0. The experiment lasted 12 weeks. Urine was collected in metabolic cages over a 24-h period. Urine was collected from the rats 2 days before the end of the experiment, and the ratio of urinary protein to urinary creatinine was measured in the clinical laboratory. All rats were examined by echocardiogram one day before the end of the experiment. On the last day of the experiment, blood was collected and sent to the laboratory for analysis. Hematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining were performed on heart and kidney sections. The ejection fraction in group 2 was lower than that in group 1 (P < 0.001). The urinary albumin to creatinine ratio in group 2 was greater than that in group 1 (P < 0.001). The urea and creatinine levels in group 1 were significantly lower than those in group 2 (P < 0.01). The levels of brain natriuretic peptide (BNP), neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C were greater in the second group than in the first group (P < 0.05). The interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) levels in group 2 were significantly greater than those in group 1 (P < 0.001). The malondialdehyde (MDA) levels in Group 2 were greater than those in Group 1 (P < 0.01). The glutathione peroxidase (GSH-Px) levels in Group 2 were lower than those in Group 1 (P < 0.05). The level of angiotensin II (AT-II) in group 1 was lower than that in group 2 (P < 0.001). Cardiac dysfunction secondary to myocardial infarction could induce cardiorenal interactions in SHRs. It could be interpreted by the activation of oxidative stress, changes in inflammation and alteration of renin-angiotensin-aldosterone system.

Smoking paradox in coronary function and structure of acute ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention.

BACKGROUND: The Smoking paradox has generated inconsistent findings concerning the clinical prognosis of acute ST-segment elevation myocardial infarction (STEMI) patients, while providing limited insights into coronary anatomy and function which are crucial prognostic factors. Therefore, this study aimed to further investigate the existence of smoking paradox in coronary anatomy and function. METHODS: This study divided STEMI patients into smokers and non-smokers. Quantitative coronary angiography, angiography­derived microcirculatory resistance (AMR) and quantitative flow ratio (QFR) were utilized to analyze coronary anatomy and function. These parameters were compared using multivariable analysis and propensity score matching. The clinical outcomes were evaluated using Kaplan-Meier curve and Cox regression. RESULTS: The study included 1258 patients, with 730 in non-smoker group and 528 in smoker group. Smokers were significantly younger, predominantly male, and had fewer comorbidities. Without adjusting for confounders, smokers exhibited larger lumen diameter [2.03(1.45-2.57) vs. 1.90(1.37-2.49), P = 0.033] and lower AMR [244(212-288) vs. 260(218-301), P = 0.006]. After matching and multivariate adjustment, smokers exhibited inversely smaller lumen diameter [1.97(1.38-2.50) vs. 2.15(1.63-2.60), P = 0.002] and higher incidence of coronary microvascular dysfunction [233(53.9%) vs. 190(43.6%), P = 0.002], but showed similar AMR and clinical outcomes compared to non-smokers. There was no difference in QFR between two groups. CONCLUSION: Smoking among STEMI patients undergoing pPCI was associated with smaller lumen diameter and higher occurrence of coronary microvascular dysfunction, although it had no further impact on clinical prognosis. The smoking paradox observed in coronary anatomy or function may be explained by younger age, gender, and lower prevalence of comorbidities.

Lack of Class I Vasoreactivity Testing for Diagnosing Patients With Coronary Artery Spasm.

BACKGROUND: Vasoreactivity testing, such as intracoronary acetylcholine (ACh) or ergometrine (EM), is defined as Class I for the diagnosis of patients with vasospastic angina (VSA) according to recommendations from the Coronary Vasomotion Disorders International Study (COVADIS) group and guidelines from the Japanese Circulation Society (JCS). HYPOTHESIS: Although vasoreactivity testing is a clinically useful tool, it carries some risks and limitations in diagnosing coronary artery spasm. METHODS: Previous reports on vasoreactivity testing for diagnosing the presence of coronary spasm are summarized from the perspective of Class I. RESULTS: There are several problems such as reproducibility, underestimation, overestimation, and inconclusive/nonspecific results associated with daily spasm. Because provoked spasm caused by intracoronary ACh is not always similar to that caused by intracoronary EM, possibly due to different mediators, supplementary use of these vasoreactivity tests is necessary for cardiologists to diagnose VSA when a provoked spasm is not revealed by each vasoactive agent. CONCLUSIONS: Cardiologists should understand the imperfection of these vasoreactivity tests when diagnosing patients with VSA.

Prognostic Value of Coronary Angiography-Derived Index of Microcirculatory Resistance in Non-ST-Segment Elevation Myocardial Infarction Patients.

BACKGROUND: The index of microcirculatory resistance is a reliable measure for evaluating coronary microvasculature, but its prognostic value in patients with non-ST-segment elevation myocardial infarction (NSTEMI) remains unclear. OBJECTIVES: This study aimed to evaluate the prognostic impact of postpercutaneous coronary intervention (PCI) angiography-derived index of microcirculatory resistance (angio-IMR) in patients with NSTEMI. METHODS: The culprit vessel's angio-IMR was measured after PCI in 2,212 NSTEMI patients at 3 sites. The primary endpoint was 2-year major adverse cardiac events (MACEs), defined as a composite of cardiac death, readmission for heart failure, myocardial reinfarction, and target vessel revascularization. RESULTS: The mean post-PCI angio-IMR was 20.63 ± 4.17 in NSTEMI patients. A total of 206 patients were categorized as the high post-PCI angio-IMR group according to maximally selected log-rank statistics. Patients with angio-IMR >25 showed a higher rate of MACEs than those with angio-IMR ≤25 (32.52% vs 9.37%; P < 0.001). Post-PCI angio-IMR >25 was an independent predictor of MACEs (HR: 4.230; 95% CI: 3.151-5.679; P < 0.001) and showed incremental prognostic value compared with conventional risk factors (AUC: 0.774 vs 0.716; P < 0.001; net reclassification index: 0.317; P < 0.001; integrated discrimination improvement: 0.075; P < 0.001). CONCLUSIONS: In patients undergoing PCI for NSTEMI, an increased post-PCI angio-IMR is associated with a higher risk of MACEs. The addition of post-PCI angio-IMR into conventional risk factors significantly improves the ability to reclassify patients and estimate the risk of MACEs. (Angiograph-Derived Index of Microcirculatory Resistance in Patients With Acute Myocardial Infarction; NCT05696379).

Numerical assessment of using various outlet boundary conditions on the hemodynamics of an idealized left coronary artery model.

Vascular diseases are greatly influenced by the hemodynamic parameters and the accuracy of determining these parameters depends on the use of correct boundary conditions. The present work carries out a two-way fluid-structure interaction (FSI) simulation to investigate the effects of outlet pressure boundary conditions on the hemodynamics through the left coronary artery bifurcation with moderate stenosis (50%) in the left anterior descending (LAD) branch. The Carreau viscosity model is employed to characterise the shear-thinning behaviour of blood. The results of the study reveal that the employment of zero pressure at the outlet boundaries significantly overestimates the values of hemodynamic variables like wall shear stress (WSS), and time-averaged wall shear stress (TAWSS) compared with human healthy and pulsatile pressure outlet conditions. However, the difference between these variables is marginally low for human healthy and pulsatile pressure outlets. The oscillatory shear index (OSI) remains the same across all scenarios, indicating independence from the outlet boundary condition. Furthermore, the magnitude of negative axial velocity and pressure drop across the plaque are found to be higher at the zero pressure outlet boundary condition.

The role of myocardial blood volume in the pathophysiology of angina with non-obstructed coronary arteries: The MICORDIS study.

BACKGROUND: Angina with Non-Obstructed Coronary Arteries (ANOCA) involves abnormal vasomotor responses. While reduced coronary flow is an established contributor to myocardial hypoxia, myocardial blood volume (MBV) independently regulates myocardial oxygen uptake but its role in ANOCA remains unclear. OBJECTIVES: We hypothesized that reduced MBV contributes to ANOCA, and associates with insulin resistance in ANOCA. METHODS: MBV in ANOCA patients was compared to age- and sex-matched healthy controls. ANOCA patients underwent coronary angiography with invasive coronary function testing (CFT) to identify vasospasm and coronary microvascular dysfunction. In all subjects MBV was quantified at baseline, during hyperinsulinemia and during dobutamine-induced stress using myocardial contrast echocardiography (MCE). The hyperinsulinemic-euglycemic clamp was used to assess insulin resistance. RESULTS: Twenty-eight ANOCA patients (21% men, 56.8 ± 8.6 years) and 28 healthy controls (21% men, 56.5 ± 7.0 years) were included. During CFT 11% of patients showed epicardial vasospasm, 39% microvascular vasospasm, 25% coronary microvascular dysfunction, and 11% of patients had a negative CFT. ANOCA patients had significant lower insulin-sensitivity (p < 0.01). During MCE, ANOCA patients showed a significantly lower MBV at baseline (0.388 vs 0.438 mL/mL, p = 0.04), during hyperinsulinemia (0.395 vs 0.447 mL/mL, p = 0.02), and during dobutamine-induced stress (0.401 vs 0.476 mL/mL, p = 0.030). CONCLUSIONS: In ANOCA patients MBV is diminished at baseline, during hyperinsulinemia and dobutamine-induced stress in the absence of differences in microvascular recruitment. These findings support the presence of capillary rarefaction in ANOCA patients. ANOCA patients showed metabolic insulin resistance, but insulin did not acutely alter myocardial perfusion.

Correlation and consistency between resting full-cycle ratio and fractional flow reserve in assessing coronary artery function in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome: a retrospective observational study.

OBJECTIVE: The study aimed to investigate the correlation and consistency between resting full-cycle ratio (RFR) and fractional flow reserve (FFR) in functional assessment of coronary arteries in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). DESIGN: Retrospective study. SETTING: A single-centre study in China. PARTICIPANTS: A total of 292 diseased vessels of 226 Chinese patients with NSTE-ACS at Cangzhou Central Hospital of Hebei Medical University from September 2021 to June 2023 were included. METHODS: The correlation between RFR and FFR, resting ratio of distal coronary artery pressure (Pd) to aortic pressure (Pa) and FFR were analysed by using Person correlation, and the consistency between RFR and FFR, resting Pd/Pa and FFR were assessed by Bland-Altman test. The diagnostic values of RFR and resting Pd/Pa for predicting FFR≤0.80 were evaluated according to the receiver operating characteristic (ROC) curves. RESULTS: RFR and resting Pd/Pa were significantly correlated with FFR, and correlation coefficients were 0.787 (p<0.001) and 0.765 (p<0.001), respectively. We found no significant differences between RFR and FFR or between resting Pd/Pa and FFR. The areas under the ROC curves for predicting FFR≤0.80 were 0.883 (p<0.001) for RFR and 0.858 (p<0.001) for resting Pd/Pa, and the optimal critical values were 0.91 for RFR and 0.93 for resting Pd/Pa. The accuracy, sensitivity, specificity and positive and negative predictive values of RFR≤0.91 for predicting FFR≤0.80 were 79.1%, 84.0%, 76.6%, 65.1% and 90.2%, respectively. CONCLUSION: The current study suggests that RFR exhibits a good correlation and consistency with FFR in patients with NSTE-ACS. RFR is expected to significantly enhance the application of coronary artery functional assessment in clinical practice, thereby providing patients with more precise revascularisation strategies.